Upon finding out that the lovely Fiona was his locker neighbor, Dallas, thinking that she was a wonder-woman-like babe, immediately made it his mission to get her to go out with him. When Fiona told him that she was a lesbian, he was shocked and wondered how such a beautiful girl could possibly be gay. He initially viewed Fiona's lesbianism as nothing but a small obstacle in his way and was convinced that she had merely not found the right guy. Fiona was unimpressed with Dallas's shameless flirting and ignorance, and decided that she wanted nothing to do with the "vile" jock.
After several failed attempts at winning her over, Dallas finally realized that Fiona would never go out with him. The two have since managed to end up on friendly terms. While a romantic relationship between the two is highly unlikely, Fiona has decided that she isn't above a little friendly flirting with Dallas every now and then. Their friendship is now put on hold ever since Dallas broke into Fiona's loft uninvited to cause conflict between him and Clare Edwards. However, they have appeared to have made up since Dallas needed someone to lean on after Cam's suicide. Fiona talked him down from the roof when he was thinking of jumping off and made him go to Tara the grief councilor. The two made up after and are now back on good terms.
In Got Your Money (1), Fiona walks up to her locker, and Dallas starts to hit on her by calling her hot and introducing himself. She isn't interested and responds by saying she's "the wrong tree to be barking up." She introduces herself and reveals to him that she is a lesbian by saying, "I love me girls." Dallas says she is way too pretty, and she introduces him to Imogen as her girlfriend, to which he replies won't buy it until they kiss. Imogen responds, "Ew," to this, and so does Fiona. He says "just one kiss," and Fiona tells him that they will when he kisses a guy on the hockey team. Imogen starts walking away, Fiona traveling behind. Imogen seems to be really uncomfortable. Fiona asks if they're going to have lunch together, and she tells Fiona that she is in a band,so she can't. Fiona says that it's silly and asks if she can even play an instrument. Imogen responds "Kind of. Gotta go." Fiona stops walking, and Dallas comes up to her, telling her, "That girl ain't no lesbian." She responds by calling him vile. When Fiona suggests having a dance that WhisperHug can play at, and Marisol likes the idea, she says she wants to make it up to Imogen for calling the band "silly." Marisol says that she has to get the hockey team behind it by talking to Mike Dallas, and Fiona isn't happy about that. Fiona tries talking to Dallas, and Dallas doesn't seem to be behind it, saying that the last time the school wanted them to be a part of something, they got humiliated. He finally agrees, but says he wants to help plan the dance and he wants to have a dance with Fiona. She once again states that she's a lesbian, but he still isn't buying it and she ends up agreeing.In Got Your Money (2), Imogen sees Fiona and Dallas and thinks they are flirting. She gets jealous by this, and Fiona explains to her that they were just joking around and that they were setting up for the dance for her band to play at. Imogen gets upset by this, thinking that Fiona just throws her an event every time she messes up. Fiona says they can talk whenever Imogen wants, and Imogen says they can't and that Fiona decided everything when she came back from New York. Fiona gets the hint that Imogen is having second thoughts about her feelings. Imogen feels like Fiona is pressuring her and Fiona tells her the pressures off and walks away, leaving Imogen to think. Fiona talks to Dallas at the dance. Fiona says Imogen and her were perfect friends but that she ruined there friendship by kissing her. She goes on saying that she doesn't know if Imogen is lesbian, bisexual, just visiting or a straight girl having a moment and that it can't be more complicated. She says that she just wants to kiss her again and there is too much talking. Dallas gives her advice, and he tells her that girls like talking and she should try to talk to Imogen and if she gets passed all the talking she can kiss her again. Fiona, taking Dallas's advice, goes and finds Imogen.
In Sabotage (2), Dallas walks over to Drew right after Drew and Fiona had a chat about Fiona throwing a surprise party for Clare. Dallas says hi but Fiona leaves and doesn't reply. She waves at him, and Drew tells Dallas about the party. Later, Dallas and some of the hockey players come to Clare's party uninvited. Fiona kicks Dallas and his hockey players out for fighting with Jake, Clare, Eli, and Katie. Dallas looking confused and says, "Fiona," but she says to get out before she calls the cops, leaving Dallas sad, bruised, and bewildered.
In Scream (1), Dallas comes to his locker and starts talking sweet to Fiona and Imogen, but Fiona responds with "Uh, you can't just start a fight at my party and think we're still buddies," and, when Dallas says "How many sorries do you need?" Imogen responds with, "YOU CAN STUFF YOUR SORRIES IN A SACK!"In Bitter Sweet Symphony (1), Dallas tries to get Fiona to put Alli on the same Spirit Week team as him, but she ultimately gives Alli a different color. Fiona apologizes to Dallas saying she can't show favoritism because of his crush, which he denies at first, but then he admits that she is hot. Dallas says that he doesn't have the best rep with Degrassi girls, which is why he doesn't just ask Alli out. Fiona agrees that Dallas has a bad reputation, but tells him maybe he can use Spirit Week to change it and win Alli over. She makes him promise to not partake in any shenanigans that week since she wants it to be perfect.
In Bitter Sweet Symphony (2), later on, Fiona hears students talking about a student on the roof. She quickly goes to the roof, only to find Dallas. She talks to Dallas as he is emotional about Cam's death, saying he caused it. She convinces him to get grief counseling at school with Tara. When he walks by to go to Grief Counseling, Fiona is glad to see him go.
In Ray of Light (1), Dallas, Fiona, Eli, and Clare are watching the new yearbook video. Dallas stops the video when Campbell is completely cut out of the Ice Hounds portions, and asks why he isn't in there. Fiona says that giving Campbell a tribute is weird messaging, but Dallas defends Campbell saying that he did still go to the school. Fiona ends up asking Eli to put him back in the video; this pleases Dallas.
- Dallas: "I'm Dallas, and you are?"
Fiona: "The wrong tree to be barking up."
Dallas: "That's a terrible name. You should change it."
Fiona: "It's Fiona Coyne. Look, I'm flattered, but not interested."
Dallas: "Well, I love me a challenge."
Fiona: "And I love me girls."
- Fiona: "Dallas! Get out before I call cops."
Fiona: "Don't...just leave."
- They were both roommates with Drew Torres.
- They were both not originally from Toronto: Fiona was born in Tokyo, Japan and moved all over the world and Dallas is from Guelph, Ontario.
- They were both friends with Adam and are both friends with Drew Torres.
- Dallas had a conflict with one of Fiona's best friends, Eli Goldsworthy though he ended his conflict with him.
- They both have a conflict with Katie Matlin.
- Fiona knew about Dallas's crush on Alli Bhandari.
- Fiona talked Dallas down from a rooftop when he was thinking irrationally.
- They were both affected by Campbell Saunders' suicide.
- They have both gone to a school rooftop because of something troubling that has occurred.
- They have both been held back a year in school, although not at the same time.
- Fiona stopped Dallas from jumping off the roof.
- They were both members of the Degrassi Student Council.